Optical image stabilization

Abstract

In an apparatus, two or more actuators perform optical image stabilization by tilting a lens module of a camera unit when installed in the camera unit between the lens module and an image sensor. A variable prism is sandwiched between the lens module and the image sensor when the apparatus is installed in the camera unit for maintaining focal plane of the lens module on the image sensor independently of optical image stabilization operations caused by the tilting of the lens module.

The invention claimed is: 
     
       1. An apparatus, comprising:
 an image sensor; 
 a lens barrel comprising and supporting one or more lenses and a bottom element; 
 two or more actuators configured to perform optical image stabilization by tilting the lens barrel with relation to the image sensor; and 
 a variable prism sandwiched between and in contact with both the bottom element and the image sensor wherein the variable prism is further configured to maintain focal plane of the one or more lenses on the image sensor independently of optical image stabilization operations caused by the tilting of the lens barrel, the variable prism being configured to remain, during movements of the bottom element, in contact with both the image sensor and the bottom element. 
 
     
     
       2. The apparatus of  claim 1 , wherein the variable prism is further configured to refract light arriving to the variable prism towards the image sensor such that tilting of the focal plane of the lens barrel with relation to the image sensor is compensated by the variable prism. 
     
     
       3. The apparatus of  claim 1 , wherein the variable prism is configured to maintain optical alignment or to reduce changes in the optical alignment between the image sensor and the lens barrel independently of the optical image stabilization operations. 
     
     
       4. The apparatus of  claim 1 , wherein the variable prism comprises transparent gel sandwiched between the bottom element and the image sensor. 
     
     
       5. The apparatus of  claim 1 , wherein the variable prism is further configured to form a dust seal between the camera sensor and the bottom element. 
     
     
       6. The apparatus of  claim 1 , comprising four of the actuators. 
     
     
       7. The apparatus of  claim 1 , wherein the actuators comprise coils configured to produce respectively controllable inductive forces for tilting the lens barrel. 
     
     
       8. The apparatus of  claim 1 , further comprising a display configured to operate as a viewfinder showing image from the image sensor while the two or more actuators perform image stabilization operations. 
     
     
       9. The apparatus of  claim 1 , further comprising a memory configured to store images captured by the image sensor. 
     
     
       10. The apparatus of  claim 4 , wherein the actuators are further configured to be operable to perform autofocus movement of the lens barrel with relation to the image sensor, and the variable prism is configured to stretch and compress according to the autofocus movements of the lens barrel. 
     
     
       11. The apparatus of  claim 4 , wherein the actuators are further configured to be operable to perform autofocus movement of the lens barrel with relation to the image sensor, and the variable prism is configured to stretch and compress according to the autofocus movements of the lens barrel; and
 wherein the variable prism is further configured to form a dust seal between the camera sensor and the bottom element. 
 
     
     
       12. The apparatus of  claim 6 , wherein the actuators are further configured operable to perform autofocus movement of the lens barrel with relation to the image sensor and the variable prism is configured to stretch and compress according to the autofocus movements of the lens barrel. 
     
     
       13. The apparatus of  claim 6 , wherein the actuators are each configured to produce controllable forces in respective sides of the lens barrel so as to tilt the lens barrel by a desired angle and to a desired direction. 
     
     
       14. The apparatus of  claim 7 , further comprising an orientation determining circuitry configured to determine at least one of present tilting and auto focus state, based on prevailing inductances of the coils. 
     
     
       15. A method, comprising:
 supporting one or more lenses and a bottom element by a lens barrel; 
 supporting an image sensor at a given distance from the bottom element; 
 supporting a variable prism sandwiched between and in contact with both the bottom element and the image sensor; 
 performing optical image stabilization by tilting the lens barrel with relation to an image sensor; 
 refracting light passing through the lens barrel to the image sensor with the variable prism; 
 maintaining focal plane of the one or more lenses on the image sensor independently of optical image stabilization operations caused by the tilting of the lens barrel; and 
 maintaining the variable prism during movements of the bottom element in contact with both the image sensor and the bottom element. 
 
     
     
       16. The method of  claim 15 , further comprising maintaining by the variable prism focal plane of the lens barrel on the image sensor independently of optical image stabilization operations caused by the tilting of the lens barrel. 
     
     
       17. The method of  claim 15 , wherein the variable prism comprises transparent gel sandwiched between the lens barrel and the image sensor. 
     
     
       18. The method of  claim 15 , further comprising performing autofocus movements of the lens barrel with relation to the image sensor and stretching and compressing the variable prism according to the autofocus movements of the lens barrel. 
     
     
       19. The method of  claim 15 , further comprising showing image from the image sensor on a display while performing image stabilization operations.